1. Field of the Invention
This invention relates to a process for making a solid rocket motor propellant grain restrictor and its application and use in the prevention of erosive burning and pressure buildup (spiking) upon ignition.
2. Description of the Prior Art
An earlier epoxy-resin-based restrictor for use with a carboxyl-terminated polybutadiene (CTPB) propellant grain for the MK56 rocket motor tends to harden excessively upon aging. This reduces restrictor strain capability and bond strength, often resulting in separation of the restrictor from the propellant. The epoxy-based restrictor also causes the CTPB propellant grain to harden, resulting in grain cracking.
These defects can cause catastrophic failure when the motor is fired. Furthermore, the epoxy-based restrictor is excessively fluid and tends to "run" after its application and before it solidifies, i.e. "cures". In order to prevent such "running", it is necessary to rotate the motor during cure, or to apply and cure the restrictor on one "flat" or "ray" of the grain perforation at a time. This results in increased man-hours for the application of the restrictor to the propellant grain.
There is a need for a restrictor which is easy to apply, cures at room temperature, and prevents cracking and hardening of the propellant grain. Such a restrictor, having superior strain and adhesive properties, is not found in the previous art.